Freeze Drying of Kombucha, Yogurt, and Kefir

The field of food preservation utilizes several methods to preserve food such as canning, drying, curing, freezing, fermenting, pickling, and freeze-drying.  Numerous dry techniques to preserve food have been explored while considering factors that can impact the microbiological, rheological, and physicochemical properties of the final food product. The process of freeze-drying is well known in the dairy and food industry mainly used for the preservation of starter cultures, probiotics, and biological material. Although an expensive method, the results obtained are in terms of better storage time, quality and viability. Stay Fresh addresses this by offering an affordable Home Freeze Dryer with industrial-grade performance. In this blog, we will briefly go over benefits of freeze drying Kombucha, Yogurt, and Kefir.

Freeze-dried starter culture resulted in kombucha with lower content of alcohol

Kombucha is a fermented tea having potential benefits for health. During the fermentation of the kombucha tea, the antioxidants are produced having some beneficial effects that increase the nutritional value of kombucha. The starter culture used for the fermentation of kombucha impacts the antioxidant activity of this traditional beverage. When the starter culture of kombucha is freeze-dried, it shifts the composition of the bacteria. The shift resulted in the changed composition of bacteria maintaining lower concentrations of ethanol and creating fewer amounts of acetic acid.

Freeze-dried starter culture resulted in increased numbers of bacteria belonging to the genus Gluconobacter in kombucha

However, the Gluconobacter genus increases after freeze-drying. The genus Gluconobacter has antifungal activity and therefore, renders the growth of yeast in kombucha. This may explain the lower alcohol content of kombucha when starter culture is freeze-dried because yeast is responsible to provide enzymes necessary for fermentation and hence alcohol production.

Freeze-dried starter culture resulted in increased concentrations of fructose and glucose in kombucha

Moreover, during the process of fermentation, the freeze-dried starter culture showed an increase in the release of reducing sugars (fructose, glucose, etc.) indicating that the freeze-drying process does not reduce the enzymatic ability of the cells. Freeze-drying the starter culture of kombucha produces less acetic acid and sucrose effectively breaks down into monosaccharides such as fructose and glucose. This gives the characteristic sweet taste to kombucha.

Addition of lyoprotectants while freeze-drying Kefir increases the viability of bacteria and yeast

Kefir is a popular probiotic beverage produced by using kefir grains. While freeze-drying kefir, when concentrations of lyoprotectants are increased, it increases the survival of yeasts and lactic acid bacteria.   

Freeze-dried yogurt has preserved nutritional values

The process of freeze drying does not affect the protein content of the yogurt while the lipid content of yogurt decreases significantly after freeze-drying. The decrease in lipid concentration may be due to the removal of aqueous residue from freeze-drying. The carbohydrate content of yogurt also does not change after freeze-drying.

Freeze-dried yogurt results in increased shelf life

Another important thing here to note is that concentrations of viable lactic acid bacteria also do not alter after freeze-drying the yogurt.  This helps in the increased shelf life of yogurt, texture, nutritional value, and health benefits. Yogurt powder can be successfully obtained from freeze-drying alongside maintaining the physical and chemical properties and the concentration of viable lactic acid bacteria in the final product.

It has never been easier to freeze dry kombucha, yogurt, or kefir at home. StayFresh technology provides affordable freeze dryer solutions for both home and small business use.

SOURCES

Effect of freeze-dried kombucha culture on microbial composition and assessment of metabolic dynamics during fermentation

The Effects of Freeze Drying and Rehydration on Survival of Microorganisms in Kefir

Evaluation of physical-chemical and microbiological characteristics of freeze-dried and reydrated yogurt